The CUSTOMERS table has these columns:
CUSTOMER_ID
NUMBER(4) NOT NULL
CUSTOMER_NAME VARCHAR2(100) NOT NULL
STREET_ADDRESSVARCHAR2(150)
CITY_ADDRESS VARCHAR2(50)
STATE_ADDRESS VARCHAR2(50)
PROVINCE_ADDRESS VARCHAR2(50)
COUNTRY_ADDRESSVARCHAR2(50)
POSTAL_CODE
VARCHAR2(12)
CUSTOMER_PHONE VARCHAR2(20)
The CUSTOMER_ID column is the primary key for the table.
You need to determine how dispersed your cutomer base is.
Which expression finds the number of different countries represented in the CUSTOMERS table?
A. COUNT(UPPER(country_address))
B. COUNT(DIFF(UPPER(country_address)))
C. COUNT(UNIQUE(UPPER(country_address)))
D. COUNT DISTINCT UPPER(country_address)
E. COUNT(DISTINCT(UPPER(country_address)))
答案为什么不是E?
